Charge support and diffuser assembly



Sept. 22, 1964 J. WHlTTEN 3,149,827

CHARGE SUPPORT AND DIFFUSER ASSEMBLY Filed April 17, 1965 2 Sheets-Sheet1 INVENTOR James L. WHITTEN ATTORNEYS.

Sept. 22, 1964 WHITTEN CHARGE SUPPORT AND DIFFUSER ASSEMBLY 2Sheets-Sheet 2 Filed April 17, 1963 N TOR.

1 V James L. MZ-l/TTEN 4 TTOENEYS United States Patent 3,149,827 CHARGESUPPORT AND DIFFUSER ASSEMBLY James L. Whitten, Lakewood, Ghio, assiguorto The Alloy Engineering Company Filed Apr. 17, 1963, Ser. No. 273,63012 Uaims. (Cl. 263-47) This invention relates generally to heat treatingapparatus, and more specifically to a new and improved charge supportand diffuser assembly for use in annealing furnaces.

In heat treating coiled metal stock, particularly in bell-type furnaces,it is the practice to support the coils vertically in stacks. Theheating of the stacked coils is accomplished largely by convection and,to this end, a suitable fan is provided in the charge supportingstructure for circulating a non-oxidizing atmosphere within a mufile orcover which encloses the charge. With this arrangement, the atmosphereflows downwardly through the center of the stack of coils into the fanand is discharged through the supporting structure around the bottom ofthe charge.

In order to promote optimum efficiency in the circulation of theatmosphere and to reduce unequal heating of the coils and otherdisadvantages due to turbulent movement of the gases, it is recognizedas being desirable to provide a vaned diffuser which will convert thehigh velocity pressure created by the fan to static pressure. Variousattempts have been made prior to this invention to provide a difiuserwhich will handle the gases efiiciently and which, at the same time, hasan economical construction strong enough to withstand the weight of thecharge.

One widely known prior art diffuser is comprised of vane assembliesformed of light bars welded together. The welded vane assembliescooperate to define outwardly diverging gas passages which have innerends extending spirally from a central opening in the diffuser andenlarged outer ends extending substantially radially. Although thisconventional construction is efficient from the standpoint of handlingthe gases, the bars making up the vanes tend to distort in use and failto support the weight of the charge. Moreover, the welded vaneconstruction is expensive and difficult to repair.

The present invention overcomes the foregoing and other disadvantages ofthe prior art, and provides a charge support and diffuser assemblyadapted efiiciently to promote good circulation of the atmosphere infurnaces such as described above. In particular, the new and improveddiifuser of this invention is adapted to make the best use of gas flowby converting the velocity pressure created by the fan to staticpressure, and to reduce turbulence in the gas flow to a minimum byproviding for uniform discharge of gas at the periphery of the diffuser.At the same time, the novel diffuser is economically constructed and isdesigned to provide good support for the heavy furnace charges withoutWarping or distorting under the high temperature conditions which areencountered. Another feature of the preferred embodiment of theinvention is the invention is that those parts of the charge support anddiffuser assembly which may be damaged or broken in any way can bereplaced and easily repaired.

Other features and advantages of the invention will be apparent from thefollowing detailed description when taken in conjunction with theaccompanying drawings.

In the drawings:

FIGURE 1 is a vertical cross-sectional view of a heat treating assemblyincorporating the novel charge support and diffuser assembly of thisinvention;

FIGURE 2 is a top plan view, with portions broken away, of the chargesupport and diffuser assembly;

3,149,827v Fatented Sept. 22, 1964 FIGURE 3 is a cross-sectional viewtaken on the line 3-3 of FIG. 2;

FIGURE 4 is a top plan view, with portions broken away and incross-section of part of the assembly comprising the invention; and

FIGURE 5 is a cross-sectional view taken on the line 5-5 of FIG. 4.

Referring now to the drawings, and to FIG. 1 in particular, theillustrated heat treating assembly includes a charge formed byvertically stacked coils 10 disposed within a mufile 11 which is used tomaintain a desired non-oxidizing atmosphere and to promote rapid heatingof the charge. The mufile 11 forms part of a conventional bell-typefurnace which will be understood to include a surrounding wall 12 thatdefines a heating chamber. This chamber is usually heated by gas-firstradiant tubes (not shown) which may be disposed in the chamher along thesides of the wall 12.

As shown, the furnace also has a steel support base 13 which issurrounded by a ledge 14. The rnufile 11 is supported on the ledge and aseal 15 of suitable material, such as a granular refractory, is formedaround the base of the mufile to reduce leakage of the non-oxidizingatmosphere. The furnace base also includes a hole 16 through whichextends the shaft of an impeller-type blower fan 17. The fan is disposedbelow the center opening 18 of the charge and is rotated by a suitablemotor (not shown) mounted beneath the base 13.

The new and improved charge support and ditfuser assembly of theinvention is indicated generally by reference numeral 25. The fan 17 ispositioned centrally within the assembly 25 which rests on the furnacebase 13, and, in turn, supports the stack of coils 10. As generallydescribed above, the non oxidizing atmosphere in the muflie flowsupwardly along the outside of the coils and downwardly through thecenter opening 18 to enter the top of the fan. The atmosphere drawn intothe rotating fan is then discharged substantially tangentially at a highvelocity pressure into the assembly 25 which, as will hereinafter bedescribed in detail, is adapted to convert the high velocity pressure tostatic pressure, while substantially eliminating turbulent gas fiow.

In order to improve the circulation of the atmosphere and effectsubstantially uniform heating of the charge, separator or convectorplates 26 are provided between the coils 10 and between the lower coilof the charge and the assembly 25. As shown in FIG. 1, each of theseseparator plates 26 defines radially extending gas channels openingalternately upwardly and downwardly, thus providing large areas of gascontact with the edges of each coil. While other forms of separatorplates can be used, the illustrated construction obtains maximum heattransfer to the coil edges, as well as good coil support. As is alsoshown in FIG. 1, an annular plate 27 having a reduced diameter is placedon the top coil over the opening 18 in order to promote flow of theatmosphere inwardly through the separator plates.

Referring now to FIGS. 2 and 3, the improved charge support and difiuserassembly 25 is shown to comprise an annular base plate 30 to theperimeter of which is secured an upstanding wrapper or rim 31. Aplurality of spaced diffuser vanes 32 are secured to the surface of thebase plate around its center opening 33. Each of the vanes 32 isgenerally triangular in the plane of the base plate 30 and has a taperedouter end 34 spaced inwardly of the wrapper, a truncated inner end 35 atthe edge of the opening 33, and an apex 36 lying on a circle between theinner and outer edges of the base plate.

In accordance with the preferred form of the invention, the vanes 32 aresolid, one-piece members cut from a thick plate. The maximum width ofeach vane at its apex 36 is preferably greater than one-half its heightamass? above the base plate. Because of this construction, the vanes 32provide a strong, stable support for the coils to be annealed and willnot buckle or distort under the load of the charge.

In addition to the val es 32, a plurality of smaller, vane separatormembers 42 are secured to the base plate at its outer edge between thetapered outer end portions 34 of adjacent vanes. As shown, each vaneseparator has inwardly converging sides 43 and 44- of unequal length,and an inner end surface The longer side 43 and the end surface 45 arerespectively parallel to the confronting sides of adjacent vanes 32. Thevanes 32 and the vane separators cooperate to define outwardly diverginggas channels 46 extending at an angle to the radius of the base plateand having outer bifurcated portions 46' and 46". The branches 46 and 46extend at an angle to each other and the width of the branches 46preferably is slightly less than the branch 46.

The illustrated form of the support and diffuser assembly includes holes4-7 which are formed through the base plate near its outer edge andwhich are spaced 180 apart. Each hole 47 communicates through thewrapper 31 by means of a pipe 43. One hole is disposed in communicationwith a gas inlet pipe (not shown) in the furnace base 13 so that thenon-oxidizing gas is introduced into the muffle 11 through the sides ofthe assembly 25. The other hole and the connecting pipe 48 is disposedin communication with a gas outlet pipe in the furnace base (also notshown) and serve as an exhaust outlet for the atmosphere. At thelocation of the holes 47, the vanes 32 are separated by trianguloidmembers 49 which are preferably used in place of the vane separators 32.

The preferred construction of the charge support and diffuser assemblyof this invention further includes a vane tip assembly 55 which isremovably mounted within the center opening 33 of the base plate. Asmost clearly shown in FiGS. 4 and 5, this vane tip assembly comprises atop ring 56 lying in the plane of the upper surfaces of the vanes 32, abottom ring 57, and a plurality of vane tips 58. The vane tips arepreferably steel castings which are welded between the rings in asymmetrical arrangement.

Each vane tip 53 forms a continuation of the truncated end 35 of one ofthe vanes 32 and has inwardly converging sides 59, 6%, and a tippedinner portion 61 at the inner edges of the rings d, 57. Thus arranged,the vane tips form throat portions for the gas channels 46, whereby thehigh velocity pressure atmosphere is discharged from the fantangentially into the diffuser. As will be apparent from FIGS. 2 and 3,the assembly of the rings 56, 57 and the vane tips 53 is inwardly spacedfrom the inner edge of the base plate 3% and the truncated ends of thevanes 32. In order to locate the assembly so that the outer ends of thevane tips are adjacent the truncated ends of the vanes 32, the outerends of four equally spaced vane tips are provided with projections 61which are engageable in channels 62 formed in the adjacent truncatedvane ends 35.

Referring again to FIGS. 2 and 3, it will be seen that an annular spacerplate as is positioned within the bottom ring 57. The shaft of the fan17 extends upwardly through the spacer plate and, if desired, an orificeplate 66 may be welded within the spacer plate to receive the shaft. Theassembly 25 is completed by an annular support plate 67 which rests onthe vanes 32 and the vane tip assembly 55. The center opening of thissupport plate 67 forms a gas flow inlet to the fan 1'7. The perimeter ofthe support plate is spaced inwardly of the wrapper 31 to provide anoutlet opening 68 for the discharge of the atmosphere from the diffuseraround the charge.

The divergence of the gas flow channels 46 from the tangential openingsor throat portions defined by the vane tips to the outlet opening 68 ofthe difiuser assembly and the division of each outwardly divergingchannel into angular related branches 46' and 46 is such as to uniformlydischarge the gas around the periphery of the diffuser assembly andthereby convert the high velocity gas pressure to static pressure withmaximum efiiciency and substantially to eliminate turbulent gas flow.One important feature of the invention is that this efficient handlingof the gas is effected by using solid vane formations. As explainedabove, this construction of the vanes provides optimum support for theweight of the charge and resists distortion when subjected to the hightemperature conditions of the furnace. At the same time, the diffuserassembly is more economical and easier to construct than the welded vaneassembly diffusers of the prior art.

Still another feature of the invention is that the vane tip assembly 55can be removed from the furnace independently of the base plate and themain vane bodies 32. This separable construction allows the vane tipseasily and quickly to be repaired and replaced should they be damaged inany way without necessitating removal and handling of the entirediffuser assembly.

Many modifications and variations of the invention will be apparent tothose skilled in the art in view of the foregoing detailed description.Therefore, it is to be understood that, within the scope of the appendedclaims, the invention can be practiced otherwise than as specificallyshown and described.

What is claimed is:

l. In a diffuser construction, a vane tip assembly comprisin flat topand bottom rings, and a plurality of spaced vane tip formations securedbetween said rings, each of the vane formations including a baseadjacent the outer edges of said rings, inwardly converging sides, and atip adjacent the inner edges of said rings, said vane tip formationsbeing symmetrically arranged to define outwardly diverging gas passages.

2. In a diffuser assembly, the structure comprising a base plate havinga central opening, a plurality of solid, one-piece vanes disposed onsaid plate and spaced around said opening, said vanes being generallytriangular in the plane of said plate and having tapered inner and outerends, the maximum width of each vane between its ends being at leastequal to one-half of its height, and a plurality of vane separatorsaround the outer edge of said base plate and extending between saidvanes, said vanes and vane separators cooperating to define outwardlyconverging gas channels.

3. A charge support and diffuser assembly comprising a plurality ofcircumferentially spaced vanes having inner ends, said spaced vanesbeing arranged to form gas channels diverging outwardly from the centerof said charge support and diffuser assembly, a centrally disposed,unitarily removable assembly of spaced vane tips, each of said vane tipsforming a continuation of the inner end of one of said vanes and beingspaced therefrom, said tips cooperating to define throat portions forsaid gas channels, and said vane tip assembly having a central openingso that a fan can be centrally posi ioned within said charge support anddiffuser assembly.

4. The assembly as claimed in claim 3 wherein said vanes and vane tipshave side surfaces, and wherein the outer end of each vane tip has atransverse dimension equal to the distance between inward projections ofsaid side surfaces of the adjacent vane so that said side surfaces ofsaid vane tips form continuations of said side surfaces of said vanes.

5. The structure as claimed in claim 3 wherein said vanes includetapered outer ends, and wherein each vane has a maximum width betweenits ends which is at least one-half of its height.

6. A charge support and difiuser assembly comprising a base plate havingan inner edge forming a central opening, a plurality of spaced vanesdisposed on said base plate and having inner ends arranged around saidopen ing, a removable vane tip assembly within said opening,

said tip assembly including a plurality of spaced vane tips each forminga continuation of the inner end of one of said vanes, means securingsaid tips together as a unitary assembly, the assembly of said tips andsecuring means being inwardly spaced from the surrounding portions ofsaid base plate and said vanes, and locating means engaging said tipassembly to hold said vane tips adjacent the inner ends of said vanes.

7. A charge support and diffuser assembly comprising in combination:

(a) a base plate,

(b) a plurality of circumferentially spaced vanes arranged on said baseplate, each of said vanes being triangular in the plane of said baseplate and including a tapered outer end adjacent the outer edge of saidbase plate, a truncated inner end, and an apex between said ends, and

(c) a removable vane tip assembly disposed centrally of said bottomplate,

(d) said vane tip assembly including a plurality of spaced vane tipseach forming a continuation of a truncated end of one of said vanes.

8. A charge support and diffuser assembly comprising in combination:

(a) an annular base plate,

(b) a plurality of solid, one-piece vanes disposed on said base plate insymmetrical, spaced arrangement,

(0) said vanes being generally triangular in the plane of said baseplate and including truncated ends at the inner edge of said base plate,outer ends adjacent the outer edge of said base plate, and apexes lyingon a circle between the edges of said base plate,

(d) vane separator members disposed around the outer edge of said baseplate between the outer end portions of said vanes, said membersincluding inwardly converging surfaces parallel to the confronting sidesurfaces of said vanes,

(e) a removable vane tip assembly disposed within the center of saidbase plate,

(f) said tip assembly including a top ring, a bottom ring, and aplurality of vane tips between said rings,

(g) each of said vane tips forming a continuation of the truncated endof one of said vanes and having an outer end at the outer edges of saidrings, inwardly converging sides, and a tipped portion at the inneredges of said rings, and

(h) annular spacer means disposed within said bottom ring.

9. A charge support and diffuser assembly comprising in combination:

(a) an annular base plate,

(b)a circumferential wrapper adjacent the periphery of said base plate,

(0) a plurality of solid, one-piece vanes disposed on said base plate insymmetrical, spaced arrangement to define outwardly diverging gaspassages,

(11) said vanes being generally triangular in the plane of said baseplate and including truncated ends at the inner edge of said base plate,outer ends adjacent said wrapper, and apexes lying on a circle betweenthe inner and outer edges of said base plate,

(e) vane separator members disposed around the outer edge of said baseplate between the outer end portions of adjacent vanes,

(7) each of said separator members having inwardly converging sidesurfaces of unequal length and an inner end surface, said inner endsurface and the longer of said side surfaces being parallel to theadjacent surface of said vanes, and

(g) a removable vane tip assembly disposed within the center of saidbase plate,

(h) said vane tip assembly including a top ring in the plane of theupper surfaces of said vanes, a bottom ring lying in the plane of saidbottom plate, and a plurality of vane tips each forming a continuationof the truncated end of one of said vanes,

(1') each of said vane tips having an end at the outer edges of saidrings, inwardly converging sides, and a tipped, inner end at the inneredges of said rings, said vane tips being symmetrically arranged todefine throat portions of said gas passages.

10. The combination as claimed in claim 9 including an annular spacerplate disposed within said bottom ring.

11. The combination as claimed in claim 10 including indexing means forlocating the outer ends of said vane tips adjacent said truncated endsof said vanes.

12. A charge support and diffuser assembly comprising in combination:

(a) an annular base plate,

(b) a plurality of vanes disposed on said base plate in symmetrical,spaced arrangement,

(c) said vanes having inner ends adjacent the inner edge of said baseplate and outer ends adjacent the outer edge of said base plate,

(d) a plurality of members disposed on said base plate, said membersextending from adjacent the outer edge of said base plate inwardlybetween said vanes and cooperating therewith to define gas channels, and

(e) a removable vane tip assembly within the center of said base plate,said vane tip assembly being spaced inwardly from the surroundingportions of said base plate and said vanes,

( said tip assembly including a top ring, a bottom ring, and a pluralityof spaced vane tips secured between said rings,

(g) each of said vane tips forming a continuation of the inner end ofone of said vanes and having an outer end, inwardly converging sides,and a tip portion, whereby said tips cooperate to define throat portionsfor said gas channels.

References Cited in the file of this patent UNITED STATES PATENTS2,731,2154 Campbell et al. Jan. 17, 1952 2,815,197 Blackman Dec. 3, 19573,039,754 Jones June 19, 1962 3,100,634 Rubrecht et al. Aug. 13, 1963FOREIGN PATENTS 1,197,727 France Dec. 2, 1959

1. IN A DIFFUSER CONSTRUCTION, A VANE TIP ASSEMBLY COMPRISING FLAT TOPAND BOTTOM RINGS, AND A PLURALITY OF SPACED VANE TIP FORMATIONS SECUREDBETWEEN SAID RINGS, EACH OF THE VANE FORMATIONS INCLUDING A BASEADJACENT THE OUTER EDGES OF SAID RINGS, INWARDLY CONVERGING SIDES, AND ATIP